Field of the Invention
The present invention relates to a light-emitting device made of a group III nitride semiconductor. More particularly, the present invention relates to such a light-emitting device characterized by the position and planar pattern of a current blockage layer.
Background Art
There has been known a technique for a light-emitting device made of a group III nitride semiconductor in which a portion of a light-emitting layer which overlaps a p-electrode in plan view is prevented from emitting light, whereby absorption of light by the p-electrode is prevented so as to improve light emission efficiency.
Patent Documents 1 and 2 disclose a light-emitting device made of a group III nitride semiconductor in which a current blockage layer made of a light transmissible insulator is provided between a p-layer and a transparent electrode in a region immediately below a p-pad electrode so as to prevent a portion of the light-emitting layer immediately below the p-pad electrode from emitting light and to cause light to be reflected at the interface between the p-layer and the current blockage layer to thereby improve light emission efficiency.
Patent Document 1: Japanese Patent Application Laid-Open (kokai) No. 2008-192710
Patent Document 2: Japanese Patent Application Laid-Open (kokai) No. 2010-232649
In the case where the current blockage layer is provided on the p-layer, the transparent electrode is provided to cover the p-layer and the current blockage layer, and the p-electrode is further provided on the transparent electrode to be located above the p-layer. Thus, through the transparent electrode, current diffuses to regions other than the region where the current blockage layer is provided. Therefore, the sheet resistance of the transparent electrode must be lowered.
However, there has been a problem in that, depending on the combination of the materials selected for the current blockage layer and the transparent electrode, the configurations of the current blockage layer and the transparent electrode, the conditions for treatment after formation, etc., the sheet resistance of the transparent electrode on the current blockage layer may increase after formation thereof, which results in an increase in the drive voltage of the light-emitting device. For example, such a problem occurs in the case where a material containing indium oxide as a main component is used to form the transparent electrode and a material containing oxygen as a constituent element, such as SiO2 or SiON, is used to form the current blockage layer.